This invention relates to an airbag system for motor vehicles. To increase safety in motor vehicles, airbags are arranged in, for example, the region of the dashboard and below the side windows. While each airbag may be provided with a separate gas source in the form of a gas generator, or a pyrotechnic device that causes the airbag to unfold when an accident occurs, it is also possible to provide a central gas source, which is connected with a plurality of airbags via pressurized gas ducts. Thus, for example, when an accident occurs the driver""s airbag and the airbag of the passenger sitting beside the driver may be inflated by a common gas generator connected to both airbags via pressurized gas ducts. The gas ducts required for this purpose may be run as pressure hoses concealed below the paneling of the motor vehicle from the gas source to the airbags, resulting in a substantial expenditure for assembly and requiring a corresponding space for assembly of the pressure hoses.
DE 4,225,709 A1 discloses that a gas generator for an airbag system may be arranged in a section of a ventilating duct of an air-conditioning device, whereby favorable tempering of the gas generator is obtained. However, no improvement in the utilization of space nor simplification of assembly with respect to the gas path between a gas generator and airbags arranged at some distance away is obtained.
It is an object of the invention to provide an improved airbag system for motor vehicles.
In accordance with the invention, the supply of pressurized gas to the airbags of a motor vehicle, which are connected to a gas source at some distance from the airbags, is effected at least partially via air-conditioning ducts of the motor vehicle. For this purpose, the pressurized gas path may be via pressure hoses in the air-conditioning ducts. Alternately, the air-conditioning ducts themselves may be designed as a portion of the pressurized path with appropriate structural integrity. The use of the air-conditioning ducts to accommodate a portion of the pressurized gas path results in optimal utilization of space as well as simplification of assembly.
If the air-conditioning ducts themselves form a part of the pressurized gas path leading to the airbags, according to a preferred embodiment of the invention it is provided that the sections used as pressurized gas ducts be capable of being isolated from other portions of the air-conditioning ducts connected to them by at least one valve. In the event of an accident and deployment of the airbags, the valves may be controlled so that the gas duct from the gas source to the respective one or more airbags forms a direct gas duct completely isolated from the air-conditioning system. In this way, a part of the air-conditioning ducts can be used to conduct pressurized gas from the gas source to the airbags, while in otherwise normal driving operation this part of the air-conditioning ducts is available for the use of the air-conditioning system.
Control of the valves may be effected by a control which detects the occurrence of an accident, and which also activates the gas source. Thus, control of the valves requires only a suitable signal connection to the signal output of the control already present.
Alternately, the valves may be designed as pressure or flow operated valves in order to accomplish the desired isolation of the air-conditioning ducts that are not used as pressurized gas ducts when an accident occurs. Reset of the valves to air-conditioning operation may be effected with a time delay, so that in the event of an accident lasting for a longer period of time the connected airbags can remain filled with gas for a longer period. A longer-lasting accident exists, for example, in the case of repeated rollover of the motor vehicle.
In another arrangement, the valves may be controlled so that, depending upon seat occupancy, not all airbags are deployed when an accident occurs. This avoids unnecessary deployment of airbags in front of empty seats.
Conventional pressure hoses may be enclosed in the air-conditioning ducts as pressurized gas ducts, or the air-conditioning duct may be designed as a one-piece dual channel part of synthetic material with an integral gas duct. Which of these two variants is to be used in the region of the air-conditioning ducts may be made dependent upon the respective structural circumstances.
The invention is described in detail below by an example, and its scope is pointed out in the claims.